This invention relates to rapid curing resin compositions, to adhesives prepared therefrom, and to methods of making and using such resins and adhesives.
U.S. Pat. No. 3,518,159; U.S. application Ser. No. 174,942, filed Aug. 25, 1971; (now U.S. Pat. No. 3,784,515) U.S. application Ser. No. 147,186, filed May 26, 1971; (now U.S. Pat. No. 3,784,514) and U.S. application Ser. No. 148,905, filed June 1, 1971; (now U.S. Pat. No. 3,784,516) each of which is assigned to the assignee of this application, collectively disclose resin products produced by reacting an aldehyde condensation polymer with a primary aromatic amine, heterocyclic amine or bis-aryl amine or acid salts of such amines. Upon blending of an appropriate hardening agent, such as formaldehyde, with the amine-modified polymers so produced, adhesives are obtained which cure very rapidly at ambient temperatures. These adhesives have particular utility as rapid-curing adhesives for wood and other materials. The amine-modified polymers specifically disclosed in the aforementioned patent and applications are organophilic as are most commercially employed construction adhesives. This is an undesirable attribute inasmuch as organic solvents must be employed to effect washing and clean-up of equipment and personnel, the use of organic solvents causing problems of flammability, toxicity, pollution and increased material costs. Because of their organophilic character, such adhesives often do not provide optimum bonding strengths on hydrophilic substrates such as wood and paper. When wood members bonded with these adhesives are to be used in high moisture environments, priming of the wood members prior to application of the adhesives is generally required to obtain superior bonding.
This invention is based on the discovery that hydrophilic resins can be produced by reacting an aldehyde condensation polymer, such as a phenol-formaldehyde condensation polymer, with a strong mineral acid salt of selected amines disclosed in the aforementiond patent and applications. Adhesives, which cure rapidly at ambient temperatures, can be prepared by combining these resins with a curing agent such as formaldehyde. The resins and uncured adhesives of this invention can be easily diluted and washed with water, and most of the resins and adhesives of this invention also wet hydrophilic substrates such as wood extremely well. However, once they have cured, the adhesives of this invention are waterproof and generally insoluble in common organic solvents.